A fourth category of obligations referred to in the Institutes of Justinian are the obligations arising from quasi-delicts (obligationes quasi ex delicto or quasi ex maleficio).

The term quasi-delictum denoted a wrongful act that did not qualify as a delictum but which nevertheless engendered an obligation between the aggrieved person and the actor, even though the latter may not in fact be blame­worthy.^[986] Justinian enumerates four kinds of wrongdoing under the heading of quasi-delicts, of which the last three appear to have related to vicarious liability.

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